Java will look for your class in the folders and file
com\toedter\calendar\JDateChooser.class

it will start this search from every directory in your CLASSPATH.
So you need to make sure you have those directories and that file in one of the CLASSPATH locations.
If you have a .jar file, java treats that just like a directory.

Not like that! Please re-read my previous post. Java will start at the classpath, then look in that location for com\toedter\calendar\JDateChooser.class You have put all those directories in the classpath, so Java is looking for
c:\java\src\com\toedter\calendar\JDateChooser\jcalendar\com\toedter\calendar\JDateChooser.class

Based on your classpath, it looks like com\toedter\calendar\JDateChooser.class can be found in c:\java\src, so that's what your classpath should be.